Larger and knobbier than a grapefruit, the fruit of Maclura pomifera — also known as the hedge apple, horse apple, green brain, and monkey ball — turns yellowish-green when it ripens in the autumn. It also develops an aroma faintly like an orange (hence the name), but it certainly doesn't taste like one. "Some authors have claimed that Native Americans had a recipe that made osage oranges palatable," wrote Nicholas P. Money in his book Mr. Bloomfield's Orchard, "but nothing touches them now. Even raccoons, opossums, and skunks who show no hesitation in consuming the rotting contents of a trash can shun the osage orange."
Curious, since as a category, fruits evolved by offering animals an equitable arrangement: Plants would offer animals something to eat, and animals would carry the plant's seeds in their digestive tracts before depositing them elsewhere, helping to spread and perpetuate the botanical species. Today, squirrels reportedly tear apart the osage orange fruit to eat the seeds, but that would defeat the plant's "purpose"; humans propagate the tree for use as a dense, thorny hedge and as a windbreak, but they have little use for the fruit. (Its folk reputation as an insect repellent is scoffed at in most scientific circles.) Why, then, does the osage orange fruit exist at all?
Connie Barlow offered a hypothesis in her 2000 article "Anachronistic Fruits and the Ghosts Who Haunt Them," and later in her book The Ghosts of Evolution. Barlow proposed that mammoths, mastodons, and other large herbivores were the osage orange's original partners in seed dispersal; she also cites research suggesting that this was true for other now-domesticated fruits including the pawpaw, persimmon, and avocado. Those partnerships ended some 13,000 years ago when the megafauna were driven to extinction — by humans, as you guessed.
Barlow also noted that a better name for the osage orange, reflecting its true botanical kin, might have been osage breadfruit. I've enjoyed roasted breadfruit at the West Indian Day Parade, but don't go roasting osage oranges yourself unless one of us can confirm they won't make you sick (who knows how, or even if, Native Americans prepared them). A safer use would be to sit an osage orange in a bowl in your pantry, to keep away the weevils. No weevils in your pantry? Great — it must be working!
Osage orange tree
Marcus Garvey Park